Methods and apparatus for operating borehole equipment



R. ROUSSIN April 13, 1965 METHODS AND APPARATUS FOR OPERATING BOREHOLE EQUIPMENT Filed Oct. 23, 1958 2 Sheets-Sheet 1 F I G 2 INVENTOR. RENE ROUSSIN FIG.

HIS ATTORNEY April 13, 1965 R. ROUSSIN I METHODS AND APPARATUS FOR OPERATING BOREHOLE EQUIPMENT Filed 061,. 23, 1958 FIG.3

2 Sheets-Sheet 2 INVENTOR. RENE ROUSSIN HIS ATTORNEY United States Patent 3,177 ,938 METHODS AND APPARATUS FOR OPERATING BOREHOLE EQUIPMENT Ren R'oussin, Marries la Coquette, France, assignor to Schlumberger Well Surveying Corporation, Houston,

Tex., a corporation of Texas Filed Oct. 23, 1958, Ser. No. 769,232 6 Claims. (Cl. 166-4) The present invention relates to methods and apparatus for operating borehole equipment and more particularly to new and improved methods and apparatus for supplying the energy necessary to operate mechanically-activated equipment within the confines of a borehole filled with drilling liquid.

This application is a continuation-in-part of the applicants copending application Serial No. 443,058, filed July 13, 1954, for Methods and Apparatus for Operating Borehole Equipment, now abandoned.

Many commercial oil field tools for use in boreholes require considerable energy for proper operation of mechanical components at given levels within a borehole. Examples of such tools are apparatus for setting packers, formation fluid samplers requiring setting against the wall of the borehole, and various logging devices in which one portion of the down-hole equipment must be moved relativeto another part. The energy required for mechanical operation of such tools may be supplied in a number of ways, for example, by translation from electrical energy transmitted from the surface of the earth, by translation from explosive energy generated in the borehole, or by translation from mechanical energy transmitted by way of drill pipe and the like.

Another successful method of supplying energy is to allow the difference in pressure betwen the hydrostatic pressure of the drilling liquid in the borehole at the level at which the tool is to be operated and the pressure in a low pressure chamber in the tool operate a piston to supply the necessary mechanical motion. While such method is effective, it will only supply energy for one operation in a well, and since the difference in pressure will depend on the level in the well, the energy supplied may be too much or too little for proper operation.

It is an object of the present invention to provide novel methods and apparatus utilizing the hydrostatic pressure of the liquid in a borehole to supply mechanical energy to operate equipment therein.

Another object of the present invention is to provide novel methods and apparatus in accordance with the foregoing in which the tool may be operated 'at successive levels in the same well.

In accordance with the present invention, the energy necessary to operate a tool in a well is obtained by utilizing the differences in the hydrostatic pressure of the well liquid at diiferent levels in the well. More particularly, the energy may be obtained by compressing gas in a chamber in said tool to the pressure of the hydrostatic head at one level in the well, and maintainingsaid gas at that pressure as the tool is passedto a different level. :a new level where it is desired to operate the tool,

and where the hydrostatic pressure is different, the difference in pressure between the gas in the chamber and the hydrostatic pressure at the new level is utilized to supply the required energy. At the same'time the gas in the chamber may be maintained compressed to the pressure of the hydrostatic pressure at the new level, the tool again movedto a diiferent level in the well for repetition of the foregoing operation. In order that the difference in pressure between the gas in the chamber and the hydrostatic pressure may not exceed desired limits, a valve may be supplied to keep this pressure diifereritial'within a predetermined maximum.

These and other objects of the present invention may be more fully understood with reference to the accompanying drawings in which:

FIG. 1 is a view of a borehole tool incorporating a typical embodiment of the invention and employed to explain the principles of operation;

FIG. 1A is a partial view of the borehole tool shown in FIG. 1;

FIG. 1B is a partial view of another valve arrangement for the borehole tool shown in FIG. 1;

FIGS. lC-lE illustrate various positions of a valve shown in FIG. 1B;

FIG. 2 is a view of well logging apparatus utilizing the present invention;

FIG. 3 is another view of the apparatus shown in 'FIG. 2, during a different period in the operation of the invention; and

FIG. 4 is yet another view of the apparatus shown in FIG. 2, during a final period in the operation of the invention.

In FIG. 1 is shown a borehole tool 10 adapted to be passed through a borehole by means of conventional electric cable 11 connected to head 12 and including an instrument 13 requiring substantial power for-proper operation, at one or more levels in the borehole. Tool 10 includes a pressure transfer chamber which is formed by an elongated cylinder or container 14 in which a piston head 15 is adapted to slide, dividing cylinder 14 into an upper chamber 16 and a lower chamber 1'7. Piston head 15 and cylinder 14 therefore define pressure transmitting means in the pressure transfer chamber. A plurality of ports 18 in upper chamber 16 admit borehole liquid therein and thus maintain the upper side of piston head 15 subject to the hydrostatic pressure of thewell as tool 10 is passed therethrough. The lower chamber 17 of cylinder 14 contains a compressible gas such as air which is maintained at a pressure related to the hydrostatic pressure of the well as a result-of the action of piston head 15.

Tool 10 has ahigh pressure elongated chamber '19 filled with a compressible gas such as air. A channel 20 interconnects chamber 19 with the lower chamber 17 of cylinder 14. A valve 21, shown as a simple ball-stop valve, in channel 20 permits gas flow from'chamber 17 to chamber 19, but prohibits flow in the other'direction. -A second channel 22 interconnects chambers 17 and 19, and a valve 23, shown as a spring-loaded ball valve, prohibits fluid flow .in channel 22 from chamber 17 to-chamber 19,

ing from chamber 19 meet at a switching valve 29 adapted to be electrically "operated from the surface of the earth suchthat channel 26 may be selectively coupled to either channel 27 or channel 28 at the discretion of the operator. The electrical wires for valve 29 are connected .to cable 11 in any well-known manner. 'In FIG. 1B, channel 26 may be coupled to channel 27 or channel '28 or both at the discretion of the operator by means of switching valve 29'.

A piston rod 30 connected to piston head 25 passes out of chamber 19 through pressure seal 31 into instrument 13 for which power to operate is desired. Piston rod 30 and thus piston head 25 may be biased downwardly by means of compression spring 32'.

at such lower level.

i of spring 32. I a

1 '-With the valve 29 as shownin FIG. 1B, operation is I similar to the above in-that the tool is lowered into the In operation, with tool at the surface, valve 29 set so that channel 26 is connected to channel 28 as shown in FIG. 1A. The tool is then lowered into the well filled with liquid, such as drilling mud, and as the depth increases the hydrostatic-pre'ssure, in upper chamber 16 of cylinder 14 increases, forcing piston head 15 downwardly and thus maintaining the gas in lower chamber 17 of cylinder 14 at the hydrostatic pressure of the drilling mud a gas in chambers 19 and 24 increases similarly.

The tool is then lowered to a level considerably lower than that at whichmechanical energy is desired to be supplied to instrument 13. At this point," chambers'17, 19 and 24 are all at the same relatively high hydrostatic pressure level. "During the raising, the hydrostatic pressure in chamber 16 decreases and likewise the air pressure in chamber 17 decreases but due to the actio'n of valve 21 the pressure in chambers 19 and 24 remains at the previous high level. 'If, however, the difierence in pressure between chambers '17 and 19 exceeds a predetermined safe amount, valve 23 will reduce the differential to the desired value.

' When the proper level is reached, the operator activates valve 29, disconnecting chamber 24 from chamber 19 and connecting chamber 24 to chamber 17. The pressure in chamber 24-is thus reduced, creating a pressure differential across piston head 25 and driving head 25 upwardly into chamber 24. Piston rod thereupon supplies themechanical energy necessary to operate instrument 13. Thus,

piston head 25 in chamber 24 are pressure responsive ac- I tuating means.

Upon completion of the operation, valve 29 may be re- 7 turned toits starting point thus interconnecting channels a .26 and 28 bringing chambers 19 and 24 in communication which permits equalization of the pressure in chambers -19 and'24 across piston head 25 and movement of the piston head in a-downward direction due to theaction well filled with liquid and as the depth increases the pressure of. the gas inchambers 17, 19 and 2.4.is increased. Valve 29 is a rotatable valve'rnember actuated by means well known in the art (not shown) between a plurality of "rotative positions; Valves'29'and 29' and means for operating the valves are conventionalas illustrated, for exlst ed., 1949. A T type fluid conduit in valve 29' in- ;cludes a channel 29b extending diametrically through valve 29' and a channel 29a extending radially and perpendicularly to channel 29b and interconnected therewith.

. 'at thelevel of tool 10. Asa resultof interconnecting channels 26. and 28 and the presence of channel 20, as 'thepressure in chamber 17 increases, the pressure of the 25 and driving head 25 upwardly into chamber 24. Piston rod 30 thereupon supplies the mechanical energy necessary to operate instrument 13.

Upon completion of the operation, valve 29 may from the position shown in FIG. 10 to the position shown in FIG. 1D, thus interconnecting channels 26, 27, 28, again bringing chambers 19 and 24 to'the. hydrostatic pressure in chamber 16. Since the'pressure on both'sides of piston I head 25 is equalized, spring 32 will retract piston rod39 I and piston head 25 into their previous position, readying instrument 13 for the next operation. Valve 29' is again The tool is then raised to the desired adjusted to interconnect channels 26 and 28 by rotating 90 counterclockwise from the position shown in FIG. 1D

to the position shown in FIG. 1B, and the tool is ready to be raised to a new level to repeat the previous operation. In accordance with the invention the foregoing operation may be made 'on descent rather than ascent. For this manner of operation, an additional control valve 20 is inserted in channel 20 permitting'the channel to be selectively opened and closed at the surface. With valve 29' set to interconnect channels 26 and 28*(FIG. 1B),

' the tool is lowered to a point above the level at which ample, inpages 1608-1610 of Tool Engineers Handbook The channels 2%, 29a of valve 29' provide interconnection of channels 26 and 28 in the position shown in FIG.

1B and the presence of channel 29 permits interconnecting of chambers 17, 19 and 24 so that as the pressure in chamber 16 increases, the pressure of the gas in chambers operation of instrument 13 is desired, the gas in chambers 17, '19 and 24 being at a pressure related to the hydrostatic pressure of the liquid 'at that level. The valve 26' in channel 20is then closed'by means operable at the surface (not shown) and the tool lowered to the newlevel, "whereby the pressure in chamber 17 is increased substautially over'the pressure in chambers 19 and 24. At the new lower level, valve 29 is activated" to rotate 45 counterclockwise from the position shown in FIG. 113 to the position shown in FIG. 1B, disconnecting chamber 24 completely and thevalve 20' in channel 20..opened injcreasing the pressure in chamber 19 to the higher pressure in chamber 17 due'to the higher-hydrostatic pressure at the new level. Piston head 25 will again supply the' necessary motion to activateinstrurnent 13. v.

Obviously many other arrangements. of valves, cham-.

1 hers. and channels maybe employed. to accomplish; the

. desired result. In addition, it is apparentthat valvearrangements may be supplied to permit operation either after ascent or descent with the same tool.

In FIGS. 2, 3 and 4am shown three views of a well tool 34 constructed in accordance with the disclosure in,

copending application Serial No. 419,678, filed March 30,

' 1954, by Saurenman and Lebourg, entitled Borehole Apparatus and-assigned to the assignee of theinstant application,.now Patent No. 2,876,413. Tool 34 has been I '36 by means of support arms 38. and- 39, and 40 and 41 are 17, 19 and 24 is also increased. 7 7

The tool is lowered to alevel considerably lower than 7 that at which mechanical energyis desired to be supplied to instrument '13. Atthis point the gas in chambers 17,

I 19 and24 are all equally pressured by the same relative] lyhigh hydrostatic pressure atsuch lowerlevel. Thertool is then raised, to thedesired level. During the raising the [hydrostatic pressure in chamber 16 decreases,*and likewise the-air pressure in chamber 17 decreases but due to V theaction of valve'21 the pressure in chambers 19 and 24 }remains at the previously high level. With valve 29 in' position as shown in FIG. 1B, when the proper level-is reached, valve 29' is actuated to rotate 180 counter clockwise to the position shown in FIG. 1C, disconnecting pads 42 and 43, respectively. A downward pressure on arms 38 and 40 at points 44 and 45 respectively is adapted ftoforce pads 42 and 43 outwardly frornframe 36 against the wall .of a borehole, anupwardjforce retracting same.

,Pads 42. and 43 are normallyre'tained inwardly by means of latches 46 and 47 forced upward by a Spring 48' over latch members 46", 47 attached to the respective M pads'42, 43. Latches 46, 47 areradapte d to be pulled downwardly by means of electromagnet 48 and latched in the downward position by dogs 61. However, a compresslon spring 49 in housing 35, through which rod 30 passes,

. tends to force pads 42 and 43 outwardly by means of slidmeans 59 and thuscollapsefspring49, andretract pads I able means 59'and links 50. An enlarged section 51 on piston rod- 30 tends when pulled upwardly to withdraw 42 and 43.

chamber 24 from chamber 19 and connecting chamber 24 V 'to chamber'17. The pressure'in chamber 24 is thus redu'ced, creating a pressure diflerential across piston head Typical characteristics of tool '34 may befas follows: 7' H With piston head 15 in its fully upward position chambers 17, 1 9 and 24 have an initial volume of 306 cubic inches;

be set, at an intermediate point by rotating counterclockwise a.) At the surface, chambers 17, 19 and 24 are loaded with an initial pressure of 1 ,000 pounds per square inch through valve 60. Safety valve'23 is'set so that the maximum differential pressure between chambers 19 and 17 will be 600 pounds per square inch. Spring 49 is a 500 pound compression spring, and a retraction of 1.3 inches will completely retrac't pads 42 and 43. With these characteristics the tool will operate down to 16,000 feet in a borehole filled with drilling mud; at 16,000 feet, the hydrostatic pressure will be approximately -10,000 pounds per square ,inch. Piston rod 30 may be activated every 1,000 feet as the tool is raised, the difference in hydrostatic pressure between two levels 1,000 feet apart being approximately 600 pounds per square inch.

In operation, with chambers 17, 19 and 24 initially loaded with air at 1,000 lbs.-'/in: with 'va1've2 9 in the .position shown, and with arms 42 and 43 latched against "frame 36, tool 34 may be lowered to opposite the lowermost portion of a well where it is desired to have pads 42 and *43 extended. When tool 34 has been lowered past the point where the hydrostatic pressure in the well is 1,000 lbs.'/in. pistonhead 15 will begin "to compress the air in chambers 17, 19, and 24, so that the air in such chambers will be at the same relatively high hydrostatic pressure of the drilling mudfiat such lowermost point.

Electromagnet 48 is now activated, pulling latch means 46 and47 downwardly and releasing pads 42 and 43. As shown in FIG. 3, spring '49 operating against driving means 59 forces pads 42 and '43 outwardly againstth wall of the borehole.

Tool 34 may now be raised, pads 42 and 43 remaining pressed against the borehole wall. While tool 34 is being raised, the pressure in chamber 17 is continuously decreasing, while the pressure in chambers 19 and 24 remains at the relatively high hydrostatic pressure of the lowermost point to which tool 34 was lowered. However, when the pressnrein chamber 17 decreases by 600 'lbsI/inl below the pressure in chambers '19 and 24,

i valve 23 will maintain the pressure differential at 600 pounds. a a

When tool 34 has been raised past that section of the well against-which it is desired to have pads-42 and "43 pressed, pads 42 and 43 should be retracted against frame 36. .If tool 34 has been raised between two lev- "els having atleast 600. lbs/in pressure differential, the

retraction operation may be begun at once; otherwise "the tool must be raised until the required pressure differential has been reached.

At this point, rotatable valve 29" is switched to the position shown in FIG. 4, and thus the pressure in chamber 24 above piston head 25 is suddenly reduced to the pressure in chamber 17. The diiference in pressure across piston head 25 forces piston rod 30 upwardly, enlarged section 51 pulling driving mechanism 59 upwardly against the counter pressure of spring 49, and retracting pads 42 and 43. The upward movement of rod 30 also releases dogs 61, whereupon spring 48' forces latches 46 and 47 into their upward position. When latches 46', 47' on retracting pads 42 and 43 reach latches 46 and 47 respectively, these pads are securely latched against frame 36. The tool is now ready to he quickly withdrawn from the borehole.

However, if additional operations are required at a higher level, valve 29" is operated as explained in connection with valves 29 and 29' to regulate the pressures in chambers 17, 19 and 24 with respect to the hydrostatic pressure of the mud at the new level. When the pressure in chambers 24 and 19 become equal, spring 32 pulls rod 30 downwardly and withdraws piston head 25 to the position shown in FIG. 2. Tool 34 may now be raised to a new level, and the pad extending and retracting operations repeated, if desired.

It will be understood that the embodiments disclosed herein are merely illustrative, and should not be considered as limiting the claims appended hereto.

,I'clairn: 1. Apparatus for operating equipment in a well bore containing 'a column of liquid comprising: a housing adapted to be passed through a well bore; a pressure transfer chamber in said housing containing a compressible fluid; a high pressure chamber in said housing con- 't'aining' a compressible fluid; pressure responsive actuat- "in'g means in said housing comprising a piston and pressure cylinder, said pressure cylinder being fluidly connected at -'one end to said high pressure' chamber thereby to expose one side of said piston to any fluid pressure in said high'pressure chamber; means connecting said pressure transferfand high pressure chambers including 'a first valve operable to control the passing "of saidcompressible fluid under pressure from said pressure transfer "chamber to said high pressure chamber; means'fluidly site said housing as said housing is passed through the well bore to transmit corresponding pressure variations to the compressible fluid in said high pressure chamber and said pressure cylinder.

2. Apparatus as in claim '1 including a passageway interconnecting said pressure transfer and high pressure chambers, and valve means in said passageway prohibiting the difference in fluid pressures between said pressure transfer and high pressure chambers from exceeding a predeterminedmaximum.

3. Apparatus for operating equipment in a well bore containing a columnjof liquid comprising: a housing having a ,pressure transfer chamber containing a cornpressible fluid and a high-pressure chamber; means to permit the liquid in the well bare to act upon the pressure transfer chamber; pressure transmitting :means in said pressure transfer chamber to isolate said compressible fluid from said well bore-liquid and transmit corresponding pressure variations to the compressible fluid therein; means fluidly interconnecting said pressure transfer and high pressure chambers including a first valve operable to control the passing of said compressible fluid under pressure from said transfer chamber to said high pressure chamber; said housing further having a portion defining a pressure cylinder fluidly connected at one end to said high pressure chamber; a piston movably positioned in said pressure cylinder and adapted to be connected to a load; means for fluidly interconnecting said pressure transfer chamber with the opposite end of said pressure cylinder and with said high pressure chamber, said means including a secondvalve selectively operable to connect either said high pressure chamber to said opposite end of said pressure cylinder or to connect said opposite end of said pressure cylinder to said transfer chamber.

4. Apparatus for operating equipment in a well bore containing a column of liquid comprising: a housing adapted to be passed through a borehole, a pressure transfer chamber in said housing; a pressure transfer piston in said pressure transfer chamber; means in said housing to admit liquid in the well bore to one side of said pressure transfer piston, the portion of the transfer chamber to the other side of said pressure transfer piston being filled with a compressible fluid, whereby the column of liquid in the well bore maintains the compressive fluid in said pressure transfer chamber at substantially the same pressure as the hydrostatic pressure of the liquid in the well bore opposite said housing as said housing is passed through the wellbore; a high pressure chamber and pressurecylinder in said housing; -aslidable piston head in said pressure cylinder; said pressure cylinder and high pressure chamber being filled with a compressible fluid, saidpressure cylinder being v. fluidly connected at one end to said high pressure chami ber'thereby to expose one side of said piston head to (any fluid pressure in said high pressure;chamber, means fluidly interconnecting said pressure transferand high I pressurechambers and including a first valve oper'a ble to control the 'passingof said compressible fluid underv pressure from said pressure transfer char'nberltosaid high pressure chamber; means for fluidly connecting said .high pressure chamber and the opposite end of said o r a r pressible fluid under, pressure from said transfer means ,to I said high pressurechambe'r and maintain thepressure ,of the compressible fluid in said high pressure chamber and the pressure of the compressible fluid in said pressure cylinder] at the highest attained jvalue; third; passage 'means for fluidly interconnectingv said pressure transfer chamber, said pressure cylinder and said'secdnd passage means, and valve means in said third passage means selectively operable to couple eithersaid pressure cylinder to said second passage means or to couple said pressure cylinder to said pressure transfer chamber. 1

pressure cylinder to one another and for fluidly connecting said pressure transfer chamber and said pressure cylinder to one: another and including second valve meansgsaid sccond valve means being :operable either to connect said high pressure chamber and said pressure] cylinder to one another or to connect said pressure transferchamber and said pressure cylinder to one another; and means connected to said piston headfor translat-i ing movement thereof to mechanical power.

V 5. Apparatus for operating equipment n'a well bore containing a column of liquid comprising: a housing adapted for passage through a well bore, said housing having a pressure transfer chamber, a high pressure chamber and a pressure cylinder each containing-acompressible fluid; said pressure cylinder opening ,to said high-pressure chambers; a' piston received'in said pres- P sure cylinder and a piston rod secured to said piston for movement therewith to actuate equipment in a well bore;

said pressure transfer chamber having an openingrto the exterior 'of the housing, pressure transmitting means-in said transfer chamber separating the liquid in the well bore from the compressible fluid in said transfer chamber,-said pressure transmitting means being responsive to the: pressure of the liquid in; the well bore-to transinit' the hydrostatic pressure of the well bore liquid to the compressible fluid; first passage means fluidly interconnecting said pressure transfer chamber to said high pressure chamber; second passage means fluidly interconnecting saidihigh pressure chamber to said pressure 1 cylinder; one way valve'means in said first passage means arranged to cont-rol'the passing of said com- 6,-A method for operating ,m'echanically driven apparatus at different levels in a well bore containing a column of liquid comprising; the step of subjecting a body of fluid in said apparatus to the hydrostatic presj sure in said column. of -liquid'at one level in the well bore; the step of isolating a portion of said body of fluid in said apparatus from the hydrostatic pressure in said column ,of liquid 'at said one level, the step of moving a said apparatus to a secondlevel in the well bore where the hydrostatic pressure of the column of liquid is different from that at said one level so' that the remaining portion of said body of fluid insaidapparatus is subjected to the hydrostatic pressure in said column-of liquid at a second level 'in the borehole, and the step of subjecting pressure responsive actuating means a to the 7 pressure of said isolated portion of said body of fluid and the pressure'of said remaining portion of said body 1 of fluid and utilizing the diiference in pressure to develop instantaneous kinetic energy-to operate the said apparatus. I e 1 v l 2 References Cited in the file of this patent UNITED STATES PATENTS 

1. APPARATUS FOR OPERATING EQUIPMENT IN A WELL BORE CONTAINING A COLUMN OF LIQUID COMPRISING: A HOUSING ADAPTED TO BE PASSED THROUGH A WELL BORE; A PRESSURE TRANSFER CHAMBER IN SAID HOUSING CONTAINING A COMPRESSIBLE FLUID; A HIGH PRESSURE CHAMBER IN SAID HOUSING CONTAINING A COMPRESSIBLE FLUID; PRESSURE RESPONSIVE ACTUATING MEANS IN SAID HOUSING COMPRISING A PISTON AND PRESSURE CYLINDER, SAID PRESSURE CYLINDER BEING FLUIDLY CONNECTED AT ONE END TO SAID HIGH PRESSURE CHAMBER THEREBY TO EXPOSE ONE SIDE OF SAID PISTON TO ANY FLUID PRESSURE IN SAID HIGH PRESSURE CHAMBER; MEANS CONNECTING SAID PRESSURE TRANSFER AND HIGH PRESSURE CHAMBERS INCLUDING A FIRST VALVE OPERABALE TO CONTROL THE PASSING OF SAID COMPRESSIBLE FLUID UNDER PRESSURE FROM SAID PRESSURE TRANSFER CHAMBER TO SAID HIGH PRESSURE CHAMBER; MEANS FLUIDLY CONNECTING SAID PRESSURE TRANSFER CHAMBER AND THE OPPOSITE END OF SAID PRESSURE CYLINDER INCLUDING A SECOND VALVE SELECTIVELY OPERABLE TO EXPOSE THE REMAINING SIDE OF SAID PISTON TO FLUID PRESSURE IN SAID PRESSURE TRANSFER CHAMBER SO THAT SAID PISTON MAY BE DISPLACED AS A RESULT OF A DIFFERENCE IN PRESSURES OCCURING IN SAID PRESSURE TRANSFER AND SAID HIGH PRESSURE CHAMBERS; MEANS MECHANICALLY CONNECTING SAID PISTON TO EQUIPMENT TO BE OPERATED IN THE WELL BORE; AND PRESSURE TRANSMITTING MEANS IN SAID PRESSURE TRANSFER CHAMBER RESPONSIVE TO VARIATIONS IN THE PRESSURE OF THE COLUMN OF LIQUID OPPOSITE SAID HOUSING AS SAID HOUSING IS PASSED THROUGH THE WELL BORE TO TRANSMIT CORRESPONDING PRESSURE VARIATIONS TO THE COMPRESSIBLE FLUID IN SAID HIGH PRESSURE CHAMBER AND SAID PRESSURE CYLINDER.
 6. A METHOD FOR OPERATING MECHANICALLY DRIVEN APPARATUS AT DIFFERENT LEVELS IN A WELL BORE CONTAINING A COLUMN OF LIQUID COMPRISING: THE STEP OF SUBJECTING A BODY OF FLUID IN SAID APPARATUS TO THE HYDROSTATIC PRESSURE IN SAID COLUMN OF LIQUID AT ONE LEVEL IN THE WELL BORE; THE STEP OF ISOLATING A PORTION OF SAID BODY OF FLUID IN SAID APPARATUS FROM THE HYDROSTATIC PRESSURE IN SAID COLUMN OF LIQUID AT SAID ONE LEVEL, THE STEP OF MOVING SAID APPARATUS TO A SECOND LEVEL IN THE WELL BORE WHERE THE HYDROSTATIC PRESSURE OF THE COLUMN OF LIQUID IS DIFFERENT FROM THAT AT SAID ONE LEVEL SO THAT THE REMAINING PORTION OF SAID BODY OF FLUID IN SAID APPARATUS IS SUBJECTED TO THE HYDROSTATIC PRESSURE IN SAID COLUMN OF LIQUID AT A SECOND LEVEL IN THE BOREHOLE, AND THE STEP OF SUBJECTING PRESSURE RESPONSIVE ACTUATING MEANS TO THE PRESSURE OF SAID ISOLATED PORTION OF SAID BODY OF FLUID AND THE PRESSURE OF SAID REMAINING PORTION OF SAID BODY OF FLUID AND UTILIZING THE DIFFERENCE IN PRESSURE TO DEVELOP INSTANTANEOUS KINETIC ENERGY TO OPERATE THE SAID APPARATUS. 